My federal tax refund for 2021 was reduced, need to understand why, got multiple choice reasons from IRS, none seem to apply, what should i do?

multiple choice reasons:
SSN was missing or incomplete - not true
Last Name of qualifying dependent does not match - not true
One or more individuals claimed as dependent exceed age limit ?- don't know my daughter is 28
AGI income exceeds $75K - not true
Amount wa computed incorrectly - not true
all choices relate to Recovery Rebate Credit ( recieved $1400) but got letter saying I received $2800

What should I do ASAP before 11/28/2022